The present invention relates to an automatic security lock assembly for a shut-off valve, particularly for a gas shut-off valve and wherein the security lock has a lock disk engageable on the gate stem head to lock the head in a shut-off position by interconnecting with a tamperproof pin-lock.
When gas needs to be shut off at a user site, a padlock usually locks the head of the gate stem with the valve body. However, because the shut-off valves are located outside a building to which gas is supplied, people can tamper with the lock and open the valve to resume gas supply. Because these valves are not inspected periodically the gas utility may supply gas to unauthorized users for long periods of time, causing losses of revenue.
With existing valves there is a concern with safety issues. It may be necessary for a customer to shut off his gas supply at the source, for instance, if there is a smell of gas due to a leak in the gas piping or equipment. Even though the valve is shut, there is presently no mechanism which ensures that the valve remains shut. Accordingly, the valve can be reopened by the customer unaware of a dangerous situation that may prevail.
It is a feature of the present invention to provide an automatic security lock for a shut-off valve, and particularly but not exclusively to a gas shut-off valve, and wherein a lock disk is installed and secured to the gate stem head to lock the head at a shut-off position by inter connecting with an automatically engaging tamper-proof pin-lock.
According to a broad aspect of the present invention there is provided a security lock assembly for a shut-off valve consisting of a valve body and an exterior engageable portion secured to a gate stem so as to rotate the stem. The body has a flange with a hole therein. The security lock assembly comprises a lock disk having a central opening for receiving the engageable portion. Abutment edges are formed integrally with the disk for engagement with the engageable portion so as to rotate therewith, and at least an indentation is formed in a bottom surface of the lock disk at a predetermined position. A pin-lock assembly is retained in the hole of the flange of the valve body. The pin-lock assembly has a pin portion upwardly biased against the lock disk. The pin portion is aligned with the indentation so as to engage therein when the valve stem is rotated to a predetermined closed position, whereby the valve is locked in the predetermined closed position by said pin portion.